Changes

==Signalment==

==Signalment==

Primary spontaneous pneumothorax is most common in large deep chested middle aged dogs. Blebs and bullae are most often found in dogs.

Primary spontaneous pneumothorax is most common in large deep chested middle aged dogs. Blebs and bullae are most often found in dogs.

Siberian Huskies seem to be predisposed to spontaneous pneumothorax.

Siberian Huskies seem to be predisposed to spontaneous pneumothorax.

Clinical signs

==Clinical Signs==

Generally acutely dyspnoeic and have a shallow rapid pattern of respiration, often accompanied by orthopnoea (breathing easily only in a standing position) and abdominal breathing. If it is caused by trauma, other injuries will often exacerbate the respiratory compromise. If a tension pneumothorax is present, the patient  will often appear barrel chested due to the increasing pressure within the thoracic cavity. An open pneumothorax can cause a range of clinical signs from mild to severe due to the communication with the exterior. Subcutaneous emphysema will be present if a concurrent pneumomediastinum exists. Decreased lung sounds will be present dorsally on auscultation, and if percussed the chest is resonant.

There will often be a history of trauma or underlying respiratory disease and the animal should be carefully examined for any other signs of trauma including [[shock]], rib fractures and concurrent thoracic injuries. Spontaneous pneumothorax may be followed by a history of recent exercise.

Cyanosis will be present if the animal is hypoxaemic due to impaired gas exchange from pulmonary atelectasis and ventilation perfusion mismatch. High intrathoracic pressures may cause reduced venous return and hence signs of decreased cardiac output e.g. pale mucous membranes and tachycardia, especially in cases oftension pneumothorax.

Thoracocentesis should be performed prior to radiographs being taken in order to stabilise the animal as this can be both diagnostic and therapeutic. Radiographs will show elevation of the heart (due to the collapse of lung lobes), lung collapse and hence movement away from the chest wall. A radiolucent area of free air where no vascular structures are present is diagnostic; this is usually most often found in the caudal thorax. The most sensitive view for diagnosis is lateral recumbency though this view is often impossible to take in a dyspnoeic animal. In these cases, a dorso-ventral view is often best . Blebs and bullae tend to be difficult to identify radiographically and may be an incidental finding. The radiographs should be carefully examined for any pulmonary pathology.  

Bronchoscopy may be necessary if there is evidence of tracheal or large airway trauma.

Treatment

Supplemental oxygen will usually be required, as is analgesia as decreasing pain will lead to improved respiration.

 

 

 

 

 

 

==Treatment==

 

Supplemental '''oxygen''' will usually be required, as is '''analgesia''' as decreasing pain will lead to improved respiration.

If the pneumothorax is small in volume (e.g. from a ruptured bullae) then rest may be all that is required if the animal is non-dyspnoeic. Small volumes will be reabsorbed over a few days and so long as they don’t reoccur no action is needed.  

If the pneumothorax is small in volume (e.g. from a ruptured bullae) then rest may be all that is required if the animal is non-dyspnoeic. Small volumes will be reabsorbed over a few days and so long as they don’t reoccur no action is needed.  

If the animal is in respiratory distress,thoracocentesis will be necessary followed by rest. Some cases can be managed by intermittent thoracocentesis, however if air is rapidly accumulating, the pneumothorax redevelops over a short period, or negative pressure is not reached at the end of aspiration then a thoracostomy tube is usually required. If thoracocentesis is required more than three times over a space of hours then a chest drain may be required.1 Cats frequently get  reexpansion pulmonary oedema following thoracocentesis.

 

When necessary, a thoracostomy tube is placed in the dorsal thorax at the level of ribs 7-8 or 8-9 directed cranioventrally into the pleural space and secured in place with a purse string suture. Radiographs should be taken after to ensure correct positioning. Continuous suction can then be used if air is rapidly accumulating.

If the animal is in respiratory distress, '''thoracocentesis''' will be necessary followed by rest. Some cases can be managed by intermittent thoracocentesis, however if air is rapidly accumulating, the pneumothorax redevelops over a short period, or negative pressure is not reached at the end of aspiration then a '''thoracostomy tube''' is usually required. If thoracocentesis is required more than three times over a space of hours then a '''chest drain''' may be required<ref>Ava Firth & Amanda Boag (2012) '''Managing the dyspnoeic emergency patient''', ''In Practice'' 2012;34:10 564-571 doi:10.1136/inp.e7376</ref>. Cats frequently get  reexpansion pulmonary oedema following thoracocentesis.

If there is a large volume of pleural air or a pulmonary lesion has been identified, surgical exploration is required to identify the source. A thoracostomy tube should be placed in all patients during surgery. If the source of the leak is not obvious during surgery, then it can be identified by filling the pleural space with saline and looking for air bubbles.  

 

When necessary, a '''thoracostomy tube''' is placed in the dorsal thorax at the level of ribs 7-8 or 8-9 directed cranioventrally into the pleural space and secured in place with a purse string suture. Radiographs should be taken after to ensure correct positioning. Continuous suction can then be used if air is rapidly accumulating.

 

If there is a large volume of pleural air or a pulmonary lesion has been identified, '''surgical exploration''' is required to identify the source. A thoracostomy tube should be placed in all patients during surgery. If the source of the leak is not obvious during surgery, then it can be identified by filling the pleural space with saline and looking for air bubbles.  

If an open pneumothorax is present then the wound should be covered and dressed to avoid further contamination before performing thoracocentesis. If a thoracostomy tube is required this should be placed on the same side of the thorax.  

If an open pneumothorax is present then the wound should be covered and dressed to avoid further contamination before performing thoracocentesis. If a thoracostomy tube is required this should be placed on the same side of the thorax.  

A chest tube should be placed prior to ventilation, and positive pressure ventilation should be avoided if a closed pneumothorax is present.  

A chest tube should be placed prior to ventilation, and positive pressure ventilation should be avoided if a closed pneumothorax is present.  

The effectiveness of treatment will be evident in a reduction in the signs of dyspnoea and can be confirmed by radiography.

The effectiveness of treatment will be evident in a reduction in the signs of dyspnoea and can be confirmed by radiography.

Prognosis

==Prognosis==

Depends on the underlying cause. If the pneumothorax is traumatic in origin then the prognosis is good if there is no other substantial thoracic trauma. Prognosis for primary spontaneous pneumothorax is usually good. If it is secondary and the underlying disease is focal and can be surgically resected then prognosis is good, if the disease is diffuse then prognosis is poor.  

 

Cats treated for spontaneous pneumothorax non surgically appear to have a better prognosis than dogs. 2

The prognosis depends on the underlying cause. If the pneumothorax is traumatic in origin then the prognosis is good provided there is no other substantial thoracic trauma. Prognosis for primary spontaneous pneumothorax is usually good. If it is secondary and the underlying disease is focal and can be surgically resected then prognosis is good, if the disease is diffuse then prognosis is poor.  

 

Cats treated for spontaneous pneumothorax non surgically appear to have a better prognosis than dogs<ref>Mooney ET, Rozanski EA, King RG, Sharp CR (2001-2010) '''Spontaneous pneumothorax in 35 cats''',  ''J. Feline Med. Surg.'', 2012 Jun;14(6):384-91</ref>

 

1 Managing the dyspnoeic emergency Patient, Ava Firth, Amanda Boag.  In Practice 2012;34:10 564-571 doi:10.1136/inp.e7376

Tilley, Larry P. , Smith Jr, Francis W.K. (2007), '''Blackwell’s Five-Minute Veterinary Consult: Canine and Feline '''(Fourth Edition) ''Blackwell Publishing''

2Mooney ET, Rozanski EA, King RG, Sharp CR. Spontaneous pneumothorax in 35 cats (2001-2010). J. Feline Med. Surg., 2012 Jun;14(6):384-91

Ettinger, Stephen J., Feldman, Edward C. (2005), '''Textbook of Veterinary Internal Medicine''' (Sixth Edition)'' Elsevier Saunders''

[[Category:Pleural Cavity and Membranes - Pathology]]

[[Category:Pleural Cavity and Membranes - Pathology]]

[[Category:Respiratory System - Degenerative Pathology]]

[[Category:Respiratory System - Degenerative Pathology]]